1. Field of the Invention
The present invention relates to a cartridge that contains print medium or ink sheets, and to a printing apparatus whose cartridge is detachable and that prints images onto print medium or the like.
2. Description of the Related Art
Conventional printing apparatuses used as output apparatuses for printing images from personal computers (PCs), digital cameras, and the like are classified into thermal printing apparatuses, inkjet printing apparatuses, laser printing apparatuses, dot matrix printing apparatuses, and so on depending on the recording technique. In particular, thermal printers utilize ink sheets and print sheets, selectively energizing multiple heating elements arrayed in the main-scanning direction and conveying the inks sheets and print sheets in the sub-scanning direction, thereby printing onto the print sheets. Due to the recent progress in devices that handle images, such as digital cameras, digital video cameras, scanners, and so on, serving as input apparatuses, thermal printers are garnering more and more attention.
Two types of thermal printers have gone into production. One has a configuration in which print sheets cut out at a set size are laminated (stacked) and are supplied in such a form, and the other has a configuration that supplies a continuous print sheet wound into a roll and cuts the print sheet to an appropriate size after printing.
Although the size is large with the configuration that cuts the roll-type print sheet, a large amount of print sheets can be supplied at once, which provides an advantage in that running costs can be significantly reduced.
A thermal printer uses metallic rollers called capstan rollers (or grip rollers) to convey the paper with high precision, which prevents the colors yellow, magenta, and cyan from becoming misaligned when those colors are overlapped and transferred. However, a paper conveyance mechanism that uses capstan rollers has a disadvantage in that a region that cannot be printed onto is present in a part of the print sheet, resulting in the occurrence of margins. Japanese Patent Laid-Open No. H10-202972 discloses a technique for reducing such margins to the greatest extent possible when using a capstan roller paper conveyance mechanism.
Because the act of printing photographs has recently increased in commercial markets, there is a significant demand for full-surface, borderless printing, with no margins; thermal printers have met this demand using the following two methods. In the first method, the print sheets are perforated in advance, and the user cuts off the end of the printed product, including the margins, along the perforation by hand after printing has finished. In the second method, a cutter provided within the device automatically cuts off the end of the printed product, including the margins. Japanese Patent Laid-Open No. 2002-301876 and Japanese Patent Laid-Open No. 2001-139212 disclose the first method, in which perforations are provided in the print sheets, and the second method, in which a cutter is provided in the printer, respectively.
While the above first method is advantageous in the sense that a cutter need not be provided within the printer and thus the device can be kept small and simple, such a method places a significant burden on the user and thus reduces the usability. Therefore the configuration that includes a cutter has been more advantageous for the user. In particular, with a printer that employs a print sheet in roll form, a cutter is already provided within the printer for the purpose of cutting the roll-type print sheet after printing, and thus the second method can be implemented without adding more components. Therefore, a printer that employs print sheets in roll form can provide printed products printed across the entire surface of the sheet, with no margins, using the second method.
FIG. 15A is a cross-section illustrating an example of the configuration of a conventional printer provided with a cutter and a print sheet in roll form, conceptually illustrating the printer at an exaggerated scale for the sake of simplicity.
In FIG. 15A, reference numeral 101 denotes a thermal head in which multiple heaters are arrayed linearly. Reference numeral 102 denotes an ink sheet that is coated with an ink layer. Reference numeral 103 denotes a platen roller provided opposite to the thermal head 101. Reference numeral 104 denotes capstan rollers, in which a driving roller and a slave roller are provided as a pair.
Reference numeral 105 denotes a cartridge housing that is detachable from the printer. Reference numeral 106 denotes a continuous print sheet, wound in roll form, that is contained in the cartridge housing 105. Reference numeral 107 denotes conveyance rollers, in which a driving roller and a slave roller are provided as a pair. Reference numeral 108 denotes discharge rollers, in which a driving roller and a slave roller are provided as a pair. Reference numeral 109 denotes a cutter member capable of cutting the print sheet 106 in roll form. Finally, reference numeral 110 denotes a cut piece collection receptacle for collecting the cut pieces cut by the cutter member 109.
As described in the above patent documents, a configuration that uses the capstan rollers 104 performs printing while conveying the print sheet 106 from the thermal head 101 toward the capstan roller 104, and thus printing is performed in the direction indicated by A in FIG. 15A. Printing is realized by pressurizing the ink sheet 102 and the print sheet 106 between the thermal head 101 and the platen roller 103, whereby heat emitted by the thermal head 101 causes the ink on the ink sheet 102 to be sublimed and thus transferred onto the surface of the print sheet 106. At the same time, the print sheet 106 is conveyed by the pair of capstan rollers 104 provided downstream from the printing direction A. In order to print subsequent colors after the first color has been printed, the pressure of the thermal head 101 is released, and the capstan rollers 104 are rotated in the direction opposite to that used during printing, returning the print sheet 106 to the starting position for printing. The second and subsequent colors are then printed using the same operation as that used for the first color.
FIG. 16 is a diagram illustrating operations performed by the conventional printer illustrated in FIG. 15A.
FIG. 16 uses arrows and the numbers (1) through (7) to illustrate the movement of the print sheet 106 throughout the procedure in which the roll-type print sheet 106 is extracted, an image is printed thereupon, and the print sheet 106 is cut and discharged. The dot-dash line P indicates the position where printing is performed; the dot-dash line C indicates the position where the cutter member 109 cuts the print sheet 106; and the dot-dash line R indicates the position where the capstan rollers 104 convey the print sheet 106.
First, the print sheet 106 is conveyed to the starting position for printing in the direction of (1).
Next, an image is printed in the direction of (2).
After that, the print sheet 106 is conveyed to the position where its forward end is to be cut, in the direction of (3).
Then, the forward end of the sheet is cut by the cutter member 109 as indicated by (4), and the cut piece is collected by the cut piece collection receptacle 110.
Next, the print sheet 106 is conveyed to the position where its rear end of the sheet is to be cut, in the direction of (5).
Finally, the rear end of the sheet is cut by the cutter member 109 as indicated by (6), and the printed product is then discharged to the exterior of the device in the direction of (7).
In order to simplify the descriptions, only a single instance of the printing process indicated by (2) is illustrated in FIG. 16. However, as described earlier, in actual color printing, the print sheet 106 makes multiple passes during the printing process of (2), whereby colors are overlapped. In addition to the three colors of yellow, magenta, and cyan, black or a protective overcoat layer on the print surface are also normally transferred, and thus the print operations are performed across three to five passes.
In this conventional example, when the cut pieces accumulate within the cut piece collection receptacle 110, the user must discard those cut pieces. Several proposals have been made for improving the operations performed by the user for discarding the cut pieces (for example, Japanese Patent Laid-Open No. 2001-163459 and Japanese Patent Laid-Open No. 2002-226096).
However, these techniques, too, ultimately provide no substitute for the user discarding the cut pieces that have accumulated in the cut piece collection receptacle 110 by hand, and thus there has been no change in the decrease in usability. Meanwhile, a configuration that puts to use the latest highly-accurate sensors and a paper conveyance mechanism, thereby eliminating the occurrence of cut pieces, has been proposed (for example, Japanese Patent Laid-Open No. 2002-103286).
FIG. 17 is a diagram illustrating the operations performed using a configuration that eliminates the occurrence of cut pieces, contrasted to those of FIG. 16.
As shown in FIG. 17, following the printing indicated by (2), in order to cut the rear end of the sheet in the processes of (5) and (6) with high accuracy, the processes of (3) and (4) in FIG. 16 are omitted. As a result, cut pieces are eliminated. However, even if the print sheet 106 is positioned according to highly-accurate sensing and then cut with the cutter member 109, it is not realistically possible to completely prevent the printed product from being skewed from the cutting line. Therefore, particularly when printing an image with high differences in contrast, such as that shown in FIG. 18A, the result is as shown in FIG. 18B or 18C, resulting in a drop in the image quality.
As described thus far, a conventional printer provided with a cutter for obtaining a printed product printed across the entire surface with the margins removed has two problems. The first problem is that the cut pieces resulting from the cutter must be discarded by the user, leading to a decrease in the usability. The second problem is that even if highly-accurate cutting that does not result in cut pieces is implemented, a slight portion of the previous or following image will remain on the primary image, leading to a drop in image quality when such an artifact is apparent.